/// <summary>
/// Convert sfnt file to woff file.
/// </summary>
/// <param name="reader">BinaryReader to read the sfnt data stream.</param>
/// <param name="writer">BinaryWriter to write the woff data.</param>
/// <param name="compression">Set to true to compress data.</param>
public static void SfntToWoff(BinaryReader reader, BinaryWriter writer, bool compression = false)
{
reader.BaseStream.Position = 0;
writer.BaseStream.Position = 0;
// Header
DataTypeConverter.WriteULong(writer, 0x774F4646); // signature
writer.Write(reader.ReadBytes(DataTypeLength.Fixed)); // flavor
writer.BaseStream.Position += DataTypeLength.ULong; // length
var numberOfTables = DataTypeConverter.ReadUShort(reader);
DataTypeConverter.WriteUShort(writer, numberOfTables); // numTables
DataTypeConverter.WriteUShort(writer, 0); // reserved
DataTypeConverter.WriteULong(writer, (uint)reader.BaseStream.Length); // totalSfntSize
DataTypeConverter.WriteUShort(writer, 1); // majorVision
DataTypeConverter.WriteUShort(writer, 0); // minorVision
DataTypeConverter.WriteULong(writer, 0); // metaOffset
DataTypeConverter.WriteULong(writer, 0); // metaLength
DataTypeConverter.WriteULong(writer, 0); // metaOriLength
DataTypeConverter.WriteULong(writer, 0); // privOffset
DataTypeConverter.WriteULong(writer, 0); // privLength
// Read original table directory
reader.BaseStream.Position += 3 * DataTypeLength.UShort;
var tags = new uint[numberOfTables];
var offsets = new uint[numberOfTables];
var compLengths = new uint[numberOfTables];
var origLengths = new uint[numberOfTables];
var origChecksum = new uint[numberOfTables];
var origOffsets = new uint[numberOfTables];
var startOffsetOfTableDirectory = writer.BaseStream.Position;
for (var i = 0; i < numberOfTables; i++)
{
tags[i] = DataTypeConverter.ReadULong(reader);
origChecksum[i] = DataTypeConverter.ReadULong(reader);
origOffsets[i] = DataTypeConverter.ReadULong(reader);
origLengths[i] = DataTypeConverter.ReadULong(reader);
}
// Table data
writer.BaseStream.Position += numberOfTables * 5 * DataTypeLength.ULong;
for (var i = 0; i < numberOfTables; i++)
{
offsets[i] = (uint)writer.BaseStream.Position;
reader.BaseStream.Position = origOffsets[i];
var tableData = reader.ReadBytes((int)origLengths[i]);
if (compression)
{
using (var compressedStream = new MemoryStream())
{
var zOutputStream = new ZOutputStream(compressedStream, zlibConst.Z_DEFAULT_COMPRESSION);
zOutputStream.Write(tableData, 0, (int)origLengths[i]);
zOutputStream.finish();
if (compressedStream.Length >= origLengths[i])
{
writer.Write(tableData);
}
else
{
compressedStream.WriteTo(writer.BaseStream);
}
}
}
else
{
writer.Write(tableData);
}
compLengths[i] = (uint)(writer.BaseStream.Position - offsets[i]);
// 4byte padding
if (writer.BaseStream.Position % 4 != 0)
{
var zeroCount = 4 - writer.BaseStream.Position % 4;
for (var j = 0; j < zeroCount; j++)
{
writer.Write((byte)0);
}
}
}
// Write table directory
writer.BaseStream.Position = startOffsetOfTableDirectory;
for (var i = 0; i < numberOfTables; i++)
{
DataTypeConverter.WriteULong(writer, tags[i]);
DataTypeConverter.WriteULong(writer, offsets[i]);
DataTypeConverter.WriteULong(writer, compLengths[i]);
DataTypeConverter.WriteULong(writer, origLengths[i]);
DataTypeConverter.WriteULong(writer, origChecksum[i]);
}
// Write length in header
writer.BaseStream.Position = 2 * DataTypeLength.ULong;
DataTypeConverter.WriteULong(writer, (uint)writer.BaseStream.Length);
}
